When the Vicious Circle Begins…

Abstract

In their study, van Schaik et al. 1 showed that cold renal perfusion during a simulation of juxtarenal aortic aneurysm repair preserved renal function and had beneficial effects on sigmoid integrity by preserving microcirculatory flow, as well as reducing oxidative stress and leucocyte infiltration. Per-operative measures to preserve renal function are still a matter of debate during open juxtarenal aortic aneurysm repair. Critics of preservation techniques state that total ischaemia times are increased by these extra procedures, thereby increasing the risk of harming post-operative renal function. However, experimental studies have demonstrated that renal hypothermia can preserve renal function through reduced oxygen consumption and per-operative measures with cooling have already been applied in humans with beneficial effects on post-operative renal function. 2 According to the European Society for Vascular Surgery guidelines, a strategy to preserve renal function by means of cold crystalloid renal perfusion may therefore be considered in patients undergoing open repair of juxtarenal abdominal aortic aneurysm. 3 Enrichment of crystalloid solution with mannitol has also been proposed, since mannitol decreases blood viscosity, induces renal vasodilatation, and produces an osmotic diuresis. Moreover, mannitol may contribute to reducing oxidative stress related to ischaemia reperfusion because it is a reactive oxygen species scavenger. 4 However, there is no compelling evidence in favour of pharmacological protection of renal function, since only limited data from underpowered studies are available. 3 Interestingly, van Schaik et al. 1 investigated the remote effects of renal cooling measures. Sigmoid damages following aortic cross clamping proximal to the renal arteries could not be attributed to the temporary exclusion of the inferior mesenteric artery, because animals were expected to have patent visceral vasculature. Accordingly, sigmoid damage was related to the remote effects of renal ischaemia reperfusion injury and consecutive oxidative stress. This is an important notion: the kidney should not be considered as a passive bystander but rather as a driving force of a detrimental spiral that can lead to multiple organ failure. 5 In fact, acute renal injury frequently occurs in combination with other organ dysfunction, such as lung injury, decreased cardiac function, or sepsis. There is therefore increasing evidence that ischaemia reperfusion injury can lead to a substantial cross talk between different organs and that acute renal injury by itself can cause deterioration of other organ's function, and thereby result in multi-organ failure. 5